1. Field of the Invention
The present invention generally relates to a digital power factor correction device, which utilizes a digital voltage loop control unit and a current loop control unit to form a two loop control mechanism and achieve a function of power factor correction.
2. The Prior Arts
The phase of input current of a power supply is different from the phase of power supply voltage due to non-linear characterization of the loading, the power factor decreases and leads to power wasting accordingly. Thus a power factor correction device is needed for establishing power factor correction to decrease necessary transmitting voltage-current of power equipment, reduce imaginary power and increase real power, and further to decrease harmonics wave interference and improve quality of power supply.
In conventional art, a power factor correction (PFC) functions by theoretically approximating input voltage waveform through adjusting input current waveform for reducing or eliminating the phase difference between current and voltage waveforms. Usually this design uses a voltage loop or current loop to control current according to loading variation. However, this design with analog circuit implementation for PFC function induces noise interference easily and, therefore, affect stability and efficiency of real operation. In addition, this kind of design lacks the simultaneous use of voltage loop and current loop for exploiting more stable control mechanism.
Therefore, it is desired to provide a power factor correction device utilizing two loops with a voltage loop and a current loop to solve the problems mentioned above.